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10 Articles in Volume 13, Issue #10
Poor Adherence to Opioid Pain Management Regimens
A Practical Approach to Discontinuing NSAID Therapy Prior to a Procedure
Opioid-induced Osteoporosis: Assessing Causes and Treatments
Persistent Acute Lower Back Pain: The Importance of Psychosocial Evaluation
Research Advance Of The Year
A Day of Consulting in Rural America
Ask the Expert: Should You Test For and Treat Opioid-induced Hypogonadism?
Ask the Expert: Do NSAIDs Cause More Deaths Than Opioids?
News Briefs
Letters to the Editor

Poor Adherence to Opioid Pain Management Regimens

Patient non-adherence to commonly used prescription protocols is a growing concern.

How well do patients understand common prescription instructions? Does twice a day mean the same thing to all patients? What about three times a day—does that mean breakfast, lunch, and dinner? Not surprisingly, a large proportion of patients do not comprehend common prescription instructions, leading to possible over- or underuse of medication.

This concern led the authors to evaluate comprehension of commonly used prescription terms. The following article reviews their results and recommendations.

Reason for Concern

Most clinicians are aware of the increasing rates of opioid prescribing over the past decade.1 Although opioids have long been used as pain management tools, this increase in prescription rates has been accompanied by concerns regarding potential adverse reactions, iatrogenic illnesses, substance abuse, and even death.2,3

More recently, some researchers have also pointed to the flip side of increased opioid prescribing—underuse of these medications. One study found that approximately 50% of patients do not take their medications as prescribed.4 Underuse, for whatever reason, can undermine the effectiveness of treatment, inflate health care costs, and result in aberrant medication behaviors such as hoarding, supplementing prescribed pain medications with other drugs that are perceived to be less risky, and poor adherence to medical treatment in general. Indeed, a team of investigators recently found that some perceived medication failures maybe a function of poor adherence rather than the value of the medication per se.5

Rates of Non-Adherence

In general, a review of the current medical literature on adherence found that published estimates of non-adherence to medications ranged from 15% to 93%. When pain management was examined specifically, the investigators found non-adherence rates ranging from 9.2% to 77.8% among cancer patients.6

Studies examining patient self-reported adherence reveal similar trends. Broekmans et al examined self-report adherence in a sample of 281 patients at a pain treatment center.7 They found a total non-adherence rate of 48%, with 14% reporting overuse, 34% reporting underuse, and 2% reporting both overuse and underuse. In a study of attitudes toward pain medications, Rosser et al found 47.6% reported underuse, 52% reported that they often skipped doses, and 23.5% to 30.4% described overuse.8

Although there clearly is a great deal of concern about overuse both in the health care arena and the public, the literature strongly suggests that underuse is much more common.

Factors Contributing To Non-Adherence


Several studies have pointed to elevated risk of overuse of opioid medications among patients with a history of substance abuse in general.9 A relationship between overuse of opioid medications and smoking cigarettes, for example, has been noted.8 Other factors noted to play a role in overuse of opioid medications include severe somatization,10 psychiatric comorbidities (substance use disorder), younger age,11 and alcohol-related arrests.12


Lewis et al identified 10 explanations patients endorsed for underusing medications13:

  • Desire to minimize medication intake in general
  • Concerns about adverse side effects and addiction
  • Desire to make the medication regimen more “acceptable”
  • Cost of medications
  • Using medications symptomatically
  • Using medications strategically (such as skipping doses in anticipation of driving)
  • Substituting or supplementing medications (using over-the-counter medications, etc.)
  • Problems with doctor-patient communication
  • Perceived medication ineffect-iveness
  • Pressure from family and friends

Complexity of Treatment

Some research suggests that the complexity of treatment is negatively correlated with treatment adherence. A review of literature on the relationship between dose regimen and medication compliance using electronic monitoring devices suggests that simpler regimens requiring fewer doses are associated with greater compliance rates.5

Type of Dosing Schedule.

One variable that appears to be associated with opioid adherence is the type of dosing schedule. Research in this area has tended to focus on time-scheduled dosing compared with pain contingent dosing. A study of cancer patients prescribed opioid analgesic medications found that those placed on time-scheduled dosing adhered 84.5% to 90.8% of the time, while those prescribed medications PRN (as needed), only adhered to medication guidelines 22.2% to 26.7% of the time.6 Time-scheduled dosing also played a role in better adherence among pediatric patients. In a study of children receiving short-term opioid treatment following tonsillectomy, investigators found that children placed on time-scheduled dosing were more adherent and achieved significantly greater pain attenuation than those receiving PRN dosing.14

Patient Comprehension of Common Prescription Instructions

Clearly, several complex factors affect treatment adherence. One obvious and commonly discussed factor is the extent to which patients comprehend the instructions provided. Although recent studies suggest that patients report feeling poorly educated and cite problems communicating with physicians, little research has examined patient comprehension of common prescription instructions. The authors conducted a study examining the extent to which patients in an outpatient pain management clinic comprehend commonly used prescription instructions.

A random sample of 300 patients with established treatment at an outpatient pain management clinic were administered a researcher-derived questionnaire during a routine follow-up visit. Participation in the study was voluntary and anonymous. A simple questionnaire developed by the researchers consisted of 6 questions designed to assess patient comprehension of some commonly used prescription instructions (Table 1). The questionnaire could easily be divided into 3 types of instructions:

  • Number of doses per day (eg, twice daily).
  • Time-scheduled dosing (eg, every 8 hours).
  • Latin abbreviation medical terms describing number of doses per day (eg, tid).

The setting of the data collection included 2 prescribing pain doctors and 3 prescribing nurse practitioners. Since the questionnaires were administered randomly and anonymously, it was not possible to examine differences in patient responses as a function of characteristics of individual prescribers.

Simple descriptive statistics were deemed sufficient to examine the extent to which participants responded accurately to each item. Inter-item comparisons were conducted using a chi square (χ2). Further, ANOVA was used to analyze the effect of complexity of treatment across item types.


Of the 300 questionnaires administered, 299 were completed appropriately and were included in the study. Limited demographic data were collected. Participants ranged in age from 22 to 93 years, with a mean age of 49.5. There were nearly twice as many females (199) as males (100). No statistically significant differences were found as a function of age or gender. All data, therefore, were collapsed for analysis.

A simple percentage was calculated reflecting the proportion of patients who answered each item on the questionnaire accurately. Percentages of patients who demonstrated accurate comprehension of common prescription instructions ranged from 16.05% to 83.61%. Several obvious inter-item comparisons were made based on the 3 categories of instructions and on the overall complexity of the treatment plan (Tables 2 and 3).


Type of Instruction

Number of doses per day vs. Time-scheduled dosing.

A comparison of items 1 and 3 showed that 28.76% more patients understood the instruction “every 12 hours” than understood the instruction “twice a day” (χ23 = 71.2, P<0.001). A comparison of items 2 and 4 showed that 25.42% more patients understood the instruction “every 8 hours” than understood the instruction “three times a day” (χ23 = 62.1, P<0.001).

Number of doses per day vs. Latin abbreviation medical terms.

A comparison of items 1 and 5 found that 24.42% more patients understood the instruction “twice a day” than the instruction “bid” (χ23 = 49.3, P<0.001). A comparison of items 2 and 6 showed that 5.69% more patients understood the instruction “three times a day” than the instruction “tid” (χ23 = 4.3, P<0.05).

Time-scheduled dosing vs. Latin abbreviation medical terms.

A comparison of items 3 and 5 showed that 53.18% more patients understood the instruction “every 12 hours” than the instruction “bid” (χ23 = 148.7, P<0.001). A comparison of items 4 and 6 showed that 31.11% more patients understood the instruction “every 8 hours” than the instruction “tid” (χ23 = 69.7, P<0.001).

Complexity of Treatment

A one-factor analysis of variance was computed to assess the extent to which complexity of treatment was related to comprehension independently of type of instruction. Data was combined into 2 groups consisting of responses to questions 1, 3, and 5 (instructions requiring 2 doses) and questions 2, 4, and 6 (instructions requiring 3 doses), with percentage correct as the dependent variable. Results suggest a strong relationship between complexity and comprehension, independent of type of question (F [3, 295] = 22.26, P<0.001).


The present data support the hypothesis that patient misunderstanding of common prescription instructions may account for some adherence problems. Depending on type of instruction, a range of 16.05% to 83.61% of patients failed to provide accurate responses to common prescription instructions. A quick glance at the data reveals a very obvious pattern of responses as a function of complexity of treatment, use of medical terminology, and what appears to be a discrepancy in defining the term “day.” This last observation deserves some further discussion.

In their treatment planning, prescribing physicians account for a 24-hour day. Thus, “twice daily” and “every 12 hours” constitute the same treatment plan. Patients, on the other hand, appear to plan their medication administrations according to the number of hours that they are awake. For example, one patient responding to the question: “If your doctor prescribes your medication for “twice a day,” at what times will you take your medication?” replied: “9:00 and 5:00.” Thus, this patient appears to be over-medicating during waking hours, and under-medicating during sleeping hours. This may result in medications dropping to sub-therapeutic levels at night, which may both disrupt sleep and result in greater pain upon waking.

One puzzling observation was that significantly more people understood the presumably more esoteric term “bid” than the seemingly straightforward “three times a day.” This observation may be an example of our finding that treatment adherence was inversely related to treatment complexity, and that complexity affects adherence independent of instruction type.


Although the present study provides some interesting data about comprehension and adherence, adherence does not necessarily predict satisfaction with treatment. Although our data appear to support time-scheduled dosing over other prescription instructions, Van Kroff et al found that patients using time-scheduled dosing expressed greater concerns about addiction, less confidence in their ability to control their medication dosing behavior, preoccupation with opioid medications, and greater concern from family and friends.15 These patients also reported greater cognitive difficulties and diminished arousal associated with opioid use.

One common prescription instruction not addressed in this study is PRN. This instruction was specifically excluded from this study as there is no way to operationalize PRN. Comprehension of this instruction, therefore, could not be evaluated against any standard.

Adherence rates likely are affected quite significantly by length of treatment. The impact of length of treatment on adherence could not be assessed by the present study.

Although the above noted limitations are an important consideration, the present study was not designed to assess satisfaction, potential side effects of medications, effectiveness of treatment, or fluctuations in rates of adherence over time. This study was designed solely to examine the extent to which patients actually understand the medication usage instructions commonly provided to them.

Very limited demographic data were collected for this study. The potential roles of educational background, socioeconomic status, ethnicity, etc., should be examined. Also, examination of clinical variables such as diagnoses, type of treatment, number of years in treatment, and comorbid medical and mental health conditions likely would provide valuable insights. Finally, no data were collected regarding the individual characteristics of the prescribers. Obviously, some prescribers may communicate with their patients better than others.

Despite some limitations, this study strongly suggests that miscommunication between physicians and patients may undermine treatment adherence substantially. Although individual characteristics of both patient and prescriber were not examined in any detail and may account for some variance, the data does strongly suggest that a substantial proportion of pain management patients do not understand commonly used prescription instructions.


Although the literature is somewhat inconsistent, some data does suggest that time-scheduled dosing may be better comprehended and result in greater treatment efficacy than other prescription instructions.6,14 It may be well worth the investment of time and effort to articulate a specific medication schedule with each patient, replacing common prescription phrases such as “twice a day” or “every 8 hours” with clock times. An individualized schedule can be agreed upon and a written medication administration form provided to the patient. Reinforcement of the agreed upon schedule and multiple iterations of the 24-hour administration cycle are likely to improve adherence to medication regimens. This form of reinforcement can easily be provided during routine follow-up and monitoring.


Last updated on: May 24, 2017
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